Showing papers in "IEEE Computer Graphics and Applications in 1993"
TL;DR: Sensation-preserving conversions for display, already known in photography, printing, and television as tone reproduction methods, are discussed and ways of constructing a sensation-preservative display converter, or tone reproduction operator, for monochrome images are demonstrated.
Abstract: Radiosity and other global illumination methods for image synthesis calculate the real world radiance values of a scene instead of the display radiance values that will represent them. Though radiosity and ray tracing methods can compute extremely accurate and wide-ranging scene radiances, modern display devices emit light only in a tiny fixed range. The radiances must be converted, but ad-hoc conversions cause serious errors and give little assurance that the evoked visual sensations are truly equivalent. Sensation-preserving conversions for display, already known in photography, printing, and television as tone reproduction methods, are discussed. Computer graphics workers can apply the existing photographic methods, but may also extend them to include more complex and subtle effects of human vision using the published findings of vision researchers. Ways of constructing a sensation-preserving display converter, or tone reproduction operator, for monochrome images are demonstrated. >
550 citations
TL;DR: A method developed to help scientists visualize 3D tensor data is presented, based on the concept of a hyperstreamline, the simplest continuous tensor structure that can be extracted from a tensor field.
Abstract: A method developed to help scientists visualize 3D tensor data is presented. The method is based on the concept of a hyperstreamline, the simplest continuous tensor structure that can be extracted from a tensor field. Hyperstreamlines for a particular case of symmetric tensor fields are introduced, and a structural depiction of symmetric tensor fields is derived from the representation of many hyperstreamlines. A method for visualizing unsymmetric tensor data by encoding an additional vector field along the trajectory of the hyperstreamlines is discussed. >
237 citations
TL;DR: A variety of methods for modeling scattered data are discussed, with an emphasis on two types of data: volumetric and spherical, to form the basis for customizing a method for a particular application.
Abstract: A variety of methods for modeling scattered data are discussed, with an emphasis on two types of data: volumetric and spherical. To demonstrate the performance of the various methods, results from an empirical study using trivariate scattered data are presented. The author's objective is to provide information to aid in selecting a type of method or to form the basis for customizing a method for a particular application. >
236 citations
TL;DR: A methodology that addresses important issues concerned with the underlying graphical models designed for surgical simulation, as well as issues related to the real-time interactivity with, and manipulation of, these models is presented.
Abstract: A methodology that addresses important issues concerned with the underlying graphical models designed for surgical simulation, as well as issues related to the real-time interactivity with, and manipulation of, these models is presented. The specific application of interest is laparoscopic surgery, which is performed using endoscopes that present a video image of the organs to the clinicians. The surgeon then performs the surgery while looking at the video monitor. The particular focus is gall bladder surgery, which involves various gastrointestinal organs. The overall objective is to simulate this environment by creating realistic, manipulable models of these organs. The models are interactively manipulable and exhibit behavior both visually acceptable and physically accurate. The approach is based on the notion of active surfaces. The rationale, mathematical formalism, and visualization techniques encompassed by the methodology are described. Recent results obtained from applying these methods to the problem of endoscopic gall bladder surgery simulation are presented. >
227 citations
TL;DR: Model-based encoding of human facial features for narrowband visual communication based on an already prepared 3D human model detects and understands a person's body motion and facial expressions and becomes the basis for modifying the 3D model of the person and thereby generating lifelike human images.
Abstract: Model-based encoding of human facial features for narrowband visual communication is described. Based on an already prepared 3D human model, this coding method detects and understands a person's body motion and facial expressions. It expresses the essential information as compact codes and transmits it. At the receiving end, this code becomes the basis for modifying the 3D model of the person and thereby generating lifelike human images. The feature extraction used by the system to acquire data for regions or edges that express the eyes, nose, mouth, and outlines of the face and hair is discussed. The way in which the system creates a 3D model of the person by using the features extracted in the first part to modify a generic head model is also discussed. >
210 citations
TL;DR: The application of 3D orthogonal wavelet transforms to real volume data is discussed and examples of the wavelet transform and the reconstruction of 1D functions are presented.
Abstract: The application of 3D orthogonal wavelet transforms to real volume data is discussed. Examples of the wavelet transform and the reconstruction of 1D functions are presented. The application of the 3D wavelet transform to real volume data generated from a series of 115 slices of magnetic resonance (MR) images is described. >
206 citations
TL;DR: The authors review the principal algorithms for the polygonization of implicit surfaces and provide a framework for identifying their conceptual similarities and practical differences and argue that consistency suffices for many purposes and is achievable with single-entry tetrahedral or cubical tables.
Abstract: The authors review the principal algorithms for the polygonization of implicit surfaces and provide a framework for identifying their conceptual similarities and practical differences. The algorithms' merits are evaluated according to topological disambiguation, implementation complexity, and triangle count. Special attention is devoted to the ambiguity problem, and proposed solutions are analyzed in the context of consistency and correctness. It is argued that consistency suffices for many purposes and is achievable with single-entry tetrahedral or cubical tables. >
198 citations
TL;DR: It is shown how the algebraic operations of pixel-wise and scalar addition and multiplication, which are the basis for many image transformations, can be implemented on compressed images.
Abstract: A family of algorithms that implement operations on compressed digital images is described. These algorithms allow many traditional image manipulation operations to be performed 50 to 100 times faster than their brute-force counterparts. It is shown how the algebraic operations of pixel-wise and scalar addition and multiplication, which are the basis for many image transformations, can be implemented on compressed images. These operations are used to implement two common video transformations: dissolving one video sequence into another and subtitling. The performance of these operations is compared with the brute-force approach. The limitations of the technique, extensions to other compression standards and the relationship of this research to other work in the area are discussed. >
194 citations
TL;DR: It is shown that some of the methods used for computing intersections of algebraic surfaces with piecewise rational polynomial parametric surface patches also apply to the generalParametric surface-intersection problem.
Abstract: Techniques for computing intersections of algebraic surfaces with piecewise rational polynomial parametric surface patches and intersections of two piecewise rational polynomial parametric surface patches are discussed. The techniques are classified using four categories-lattice evolution methods, marching methods, subdivision methods, and analytic methods-and their principal features are discussed. It is shown that some of these methods also apply to the general parametric surface-intersection problem. >
156 citations
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TL;DR: The shell concept, the data structure, the rendering and measurement algorithms, and examples drawn from medical imaging that illustrate these concepts are described.
Abstract: A structure model for volume rendering, called a shell, is introduced. Roughly, a shell consists of a set of voxels in the vicinity of the structure boundary together with a number of attributes associated with the voxels in this set. By carefully choosing the attributes and storing the shell in a special data structure that allows random access to the voxels and their attributes, storage and computational requirements can be reduced drastically. Only the voxels that potentially contribute to the rendition actually enter into major computation. Instead of the commonly used ray-casting paradigm, voxel projection is used. This eliminates the need for render-time interpolation and further enhances the speed. By having one of the attributes as a boundary likelihood function that determines the most likely location of voxels in the shell to be on the structure boundary, surface-based measurements can be made. The shell concept, the data structure, the rendering and measurement algorithms, and examples drawn from medical imaging that illustrate these concepts are described. >
147 citations
TL;DR: It is suggested that ultrasound data acquisition will play an increasing role in the future of medical imaging because it offers interactive visualization of underlying anatomy in real time.
Abstract: It is suggested that ultrasound data acquisition will play an increasing role in the future of medical imaging. Unlike magnetic resonance imaging (MRI) and computerized tomography (CT), ultrasound offers interactive visualization of underlying anatomy in real time. Additionally, ultrasound equipment costs far less and does not use ionizing radiation or require specialized facilities. The different methods for multidimensional medical imaging and scientific visualization are reviewed. Several volume visualization algorithms are discussed. They are multiplexer slicing, surface fitting, volume rendering, data classification, and viewing and shading. Three-dimensional ultrasound data display methods are also discussed. >
TL;DR: A method for applying systems of constraints at one or more arbitrary points on a single or composite curve and an efficient technique for the interactive application of these systems are outlined.
Abstract: Alternative techniques for control-vertex manipulation of parametric curves are described. Their generality and flexibility make possible a wide range of curve-editing interfaces based on direct manipulation. A method for applying systems of constraints at one or more arbitrary points on a single or composite curve and an efficient technique for the interactive application of these systems are outlined. Analytic solutions and examples for useful systems of constraints are presented. >
TL;DR: A surface-based approach to variational modeling is discussed and the approach is applied to solving the problems of eliminating rigid-body motion, handling incidence and tangency constraints, and modeling form variations.
Abstract: A variational model is a computer representation of a variational class and stands for a collection of different instances of the part or assembly modeled in CAD. The different basic approaches to variational modeling are reviewed. A surface-based approach to variational modeling is discussed. The approach is applied to solving the problems of eliminating rigid-body motion, handling incidence and tangency constraints, and modeling form variations. The application of variational modeling to automated tolerance analysis is also discussed. >
TL;DR: An algorithm for triangulating 2-D data points that is based on a uniform grid structure and a triangulation strategy that builds triangles in a circular fashion is discussed and two ways to compute the convex hull using the algorithm are presented.
Abstract: An algorithm for triangulating 2-D data points that is based on a uniform grid structure and a triangulation strategy that builds triangles in a circular fashion is discussed. The triangulation strategy lets the algorithm eliminate points from the internal data structure and decreases the time used to find points to form triangles, given an edge. The algorithm has a tested linear time complexity that significantly improves on that of other methods. As a by-product, the algorithm produces the convex hull of the data set at no extra cost. Two ways to compute the convex hull using the algorithm are presented. The first is based on the edge list and the second is based on the grid structure. >
TL;DR: An extension to the n-Vision visualization system, which provides users with a 3D virtual world within which they can visualize and manipulate representations of multivariate relations is discussed, is an rule based system that eliminates the difficulty in choosing among the many alternative when designing visualizations.
Abstract: An extension to the n-Vision visualization system, which provides users with a 3D virtual world within which they can visualize and manipulate representations of multivariate relations is discussed. The extension, AutoVisual, is rule based system that eliminates the difficulty in choosing among the many alternative when designing visualizations. AutoVisual designs interactive virtual worlds for visualizing and exploring multivariate relations. It is guided by user-specified visualization tasks and a rule base of design principles. AutoVisual's visualization techniques and the visualization tasks it handles are described. Example visualizations AutoVisual has generated for two problem domains are discussed. >
TL;DR: The role of implicit curves and surfaces in computer-aided geometric design (CAGD) are described and techniques used to circumvent conversions between implicit and parametric representations are discussed.
Abstract: The role of implicit curves and surfaces in computer-aided geometric design (CAGD) are described. The ways in which the study of implicit algebraic curves and surfaces draws on algebraic geometry are reviewed. The implicitization of parametric curves and surfaces, parameterization of implicits, and techniques used to circumvent conversions between implicit and parametric representations are discussed. >
TL;DR: A technique for rendering particles in general, and surface particles in particular, is presented that incorporates an improved shading model, the use of Gaussian filters to prevent spatial and temporal artifacts, and an efficient scan-conversion algorithm.
Abstract: A technique for rendering particles in general, and surface particles in particular, is presented. This technique incorporates an improved shading model, the use of Gaussian filters to prevent spatial and temporal artifacts, and an efficient scan-conversion algorithm. The steps of the rendering are described: shading, filtering, scan conversion, and occlusion. Ways in which the process may be varied to further improve the results and widen the range of applications are discussed. >
Journal Article•
TL;DR: The main goal is to encourage the use of studies in visualization, but it is recognized that other disciplines also offer important insights into visualization design, for example, the areas of visual design or the visual arts.
Abstract: Visualization as currently practiced is mostly a craft. Methods are often designed and evaluated by presenting results informally to potential users. No matter how efficient a visualization technique may be, or how well motivated from theory, if it does not convey information effectively, it is of little use. User studies offer a scientifically sound method to measure a visualization’s performance. Although their use has become more widespread, we believe they have the potential for a much broader impact. This article describes our experiences with user studies. We offer some examples of our own studies, talk about the pitfalls and problems we encountered, and show how the results were applied to produce successful visualizations. Although our main goal is to encourage the use of studies in visualization, we recognize that other disciplines also offer important insights into visualization design, for example, the areas of visual design or the visual arts. We conclude by discussing when knowledge from these areas might be preferable to a traditional user study.
TL;DR: It is suggested that DCTs are more popular because fewer DCT coefficients than DFT coefficients are needed to get a good approximation to a typical signal, since the higher-frequency coefficients are small in magnitude and can be more crudely quantized than the low-frequency coefficient.
Abstract: Discrete cosine transforms (DCTs) and discrete Fourier transforms (DFTs) are reviewed in order to determine why DCTs are more popular for image compression than the easier-to-compute DFTs. DCT-based image compression takes advantage of the fact that most images do not have much energy in the high-frequency coefficients. It is suggested that DCTs are more popular because fewer DCT coefficients than DFT coefficients are needed to get a good approximation to a typical signal, since the higher-frequency coefficients are small in magnitude and can be more crudely quantized than the low-frequency coefficients. >
TL;DR: Triangulations, which play an important role in approximation theory, finite-element methods, numerical analysis, and computer-aided geometric design (CAGD), are defined.
Abstract: Triangulations, which play an important role in approximation theory, finite-element methods, numerical analysis, and computer-aided geometric design (CAGD), are defined. Triangulations in the plane, in space, and on the surface of a sphere are discussed. The storing and construction of triangulations are also discussed. >
TL;DR: Tensor product surfaces, the most popular surfaces in computer-aided geometric design, true surfaces, Bezier triangles, B-patches, and a triangular B-spline scheme that combines B-Patches and simplex splines are discussed.
Abstract: Polar forms, which simplify the construction of polynomial and piecewise-polynomial curves and surfaces and lead to new surface representations and algorithms, are reviewed. The polar forms of polynomial curves, Bezier curves, and B-spline are discussed. Tensor product surfaces, the most popular surfaces in computer-aided geometric design, true surfaces, Bezier triangles, B-patches, and a triangular B-spline scheme that combines B-patches and simplex splines are also discussed. >
TL;DR: It is shown that Dupin cyclides, as surfaces in computer-aided geometric design (CAGD), have attractive properties such as low algebraic degree, rational parametric forms, and an easily comprehensible geometric representation using simple and intuitive geometric parameters.
Abstract: It is shown that Dupin cyclides (C.P. Dupin, 1822), as surfaces in computer-aided geometric design (CAGD), have attractive properties such as low algebraic degree, rational parametric forms, and an easily comprehensible geometric representation using simple and intuitive geometric parameters. Their alternative representations permit the transition between forms when one or the other is more convenient for a specific purpose. Cyclides provide is useful extension of geometric coverage in solid modeling, primarily as blending surfaces for many commonly occurring situations. The geometry, properties, and uses of the Dupin cyclide in free-form surface modeling and blending are discussed. >
TL;DR: Although the spline interpolation of the bone surface does not produce a realistic 3-D visualization of the tibia, which is used as an example, the reconstruction is useful in solving problems inherent in the pathology considered.
Abstract: A system for evaluating bone deformities using a 3-D model directly recovered from 2-D images and for simulating surgery is described. It derives a 3-D object representation from only two X-ray images. It also offers user-friendly simulation of bone surgery with low-cost hardware and software. The system exhibits satisfactory behavior for reconstructing the bone shape, providing suitable data for the simulation and evaluation of bone surgery. Although the spline interpolation of the bone surface does not produce a realistic 3-D visualization of the tibia, which is used as an example, the reconstruction is useful in solving problems inherent in the pathology considered. >
TL;DR: An experimental computer-aided design tool that actively assists in conceptual industrial design of consumer electronics products with injection-molded housings is discussed and examples are presented to show that the system can create designs both meaningful to humans and distinctive in style over a range of products.
Abstract: An experimental computer-aided design tool that actively assists in conceptual industrial design of consumer electronics products with injection-molded housings is discussed. This concept phase design tool uses manufacturing, ergonomic, aesthetic, and styling considerations to improve the entire product development process. The model's organization level performs spatial partitioning of components. The surfacing level generates an enclosure for product design. The third level adds style-specific details, and the fourth level applies graphical elements such as color or decals. Examples are presented to show that the system can create designs both meaningful to humans and distinctive in style over a range of products. >
IBM1
TL;DR: An algorithm for parallel volume rendering on general-purpose workstations connected to a local area network (LAN) is presented and it is concluded that minimal additional computing and communication are required if each processor is given the task of computing sequences of successive lines in the image.
Abstract: An algorithm for parallel volume rendering on general-purpose workstations connected to a local area network (LAN) is presented. The algorithm is based on an efficient scan-line algorithm for volume rendering of irregular meshes. This algorithm computes images by intersecting the mesh with successive planes defined through each scan line and perpendicular to the screen. These planes are called scan planes. Image coherency from one scan plane to the next, and within each scan plane, speeds up image computation. The proposed algorithm is a modified version of the scan-line algorithm, suitable for parallelization and for handling large data sets efficiently. Based on an efficiency analysis of this version, it is concluded that minimal additional computing and communication are required if each processor is given the task of computing sequences of successive lines in the image. Ways of achieving good load balancing on a group of heterogeneous workstations that have arbitrary loads by other users are suggested. >
TL;DR: The Scan Analysis and Visualization Processor (Scan/VP), a flexible, portable, Unix-based software package for visualizing and analyzing positron emission tomography images in a clinical-research setting, is described.
Abstract: The Scan Analysis and Visualization Processor (Scan/VP), a flexible, portable, Unix-based software package for visualizing and analyzing positron emission tomography (PET) images in a clinical-research setting, is described. PET systems are compared to computerized tomography (CT) and magnetic resonance imaging (MRI) systems. The imaging and software aspects of Scan/VP, and procedures devoted specifically to functional PET imaging, including mathematical modeling, image registration, regional thresholding, and derivation of regional covariation patterns, are discussed. Basic surface display, animation, and stereo techniques for visualizing variations in metabolic topology and underlying disease patterns are also discussed. >
TL;DR: The transport theory model is used to illustrate why DVDDs are best able to support fast presentation from arbitrary directions and the technology underlying various DVDDs is described.
Abstract: Direct volume display devices (DVDDs), which display 3D volumes and surfaces in a volume by providing depth rather than depth cues, are discussed. The transport theory model is used to illustrate why DVDDs are best able to support fast presentation from arbitrary directions. The technology underlying various DVDDs is described. Specifically, the design and operation of the OmniView rotating-screen DVDD are examined. The air-traffic-control/air-tactics-analysis, satellite orbit mechanics, and time-critical target prosecution applications of DVDDs are also discussed. >
TL;DR: Techniques for visualizing several climate variables, particularly clouds and wind velocities, are discussed in the context of a high-definition television animation produced to show global cloud motion during ten simulated days in January.
Abstract: Techniques for visualizing several climate variables, particularly clouds and wind velocities, are discussed. The techniques are volume rendering, textured contour surfaces, and vector field rendering. The application of these techniques is discussed in the context of a high-definition television (HDTV) animation produced to show global cloud motion during ten simulated days in January. The computational grid is defined by nearly a million grid points-320 evenly spaced longitudes, 160 unevenly spaced latitudes, and 19 unevenly spaced surfaces of constant geopotential. The climate variables at every grid point were output at every hour of simulated time, resulting in 380 MB of data per simulated day. >
TL;DR: A parallel intersection algorithm for speeding the creation of a composite network of polygons whose identities relate to the original polygons from which they are formed in vector geographic information systems (ISs) is described.
Abstract: A parallel intersection algorithm for speeding the creation of a composite network of polygons whose identities relate to the original polygons from which they are formed in vector geographic information systems (ISs) is described. The algorithm reduces unnecessary intersection checking, especially when polygon density is high. Single-stream and multiple-stream versions of the algorithm are discussed. Experimental results illustrating the overall performance of the parallel algorithm are presented. >
Journal Article•
TL;DR: This method creates a 3D facial model of a specific person using just two images of the face - a front and a side view- and a generic head model.
Abstract: This method creates a 3D facial model of a specific person. It uses just two images of the face - a front and a side view- and a generic head model